Mercury

Orbital eccentricityMercury has the most elliptical (or least circular) orbit of all the planets in our solar system. At the scale of this diagram, Mercury is about 8 feet closer to the Sun when at perihelion, and its aphelion is a corresponding distance farther out. So, depending where Mercury is in its orbit, light from the Sun takes between 2.5 minutes and 3.8 minutes to reach the planet. How long does it take you to walk from the Sun marker to the Mercury marker? If you can do it in less than 2.5 minutes, then (at the scale of this Solar System model) your normal walking speed is faster than the speed of light!

More interesting facts

Mercury is the smallest planet in our solar system.

During Mercury’s daytime, the temperature can reach up to about 800 degrees Fahrenheit.

But since it has almost no atmosphere with which to retain heat, Mercury’s nighttime temperature drops by more than 1000 degrees.

In fact, scientists theorize that there is ice on Mercury, in craters near its poles (which are in perpetual shadow).

The Mercury image on this page was taken in 2012 by the Messenger probe, and is courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.​If you arrived at this page by scanning a QR code, and want more information, please see the Introduction page.